Guerbet alcohols have been known for over 100 years now. Marcel Guerbet pioneered the basic chemistry in the 1890s. It has allowed for the synthesis of a regiospecific beta branched hydrophobe which introduces high purity, branching into the molecule.
Guerbet alcohols have been known since the 1890's when Marcel Guerbet first synthesized these materials. The reaction sequence, which bears his name, is related to the Aldol Reaction and occurs at high temperatures under catalytic conditions. The overall reaction can be represented by the following equation;

The product is an alcohol with twice the molecular weight of the reactant alcohol minus a mole of water. The reaction proceeds by a number of sequential steps. These steps including (a) oxidation of alcohol to aldehyde, (b) aldol condensation after proton extraction, (c) dehydration of the Aldol product, (d) hydrogenation of the allylic aldehyde.
The reaction takes place without catalyst, but it is strongly catalyzed by addition of hydrogen transfer catalysts. At low temperatures 130–140° C. the rate-limiting step is the oxidation process (i.e. formation of the aldehyde). At somewhat higher temperatures 160–180° C. the rate-limiting step is the Aldol Condensation. At even higher temperatures other degradative reactions occur and can become dominant.
Many catalysts have been described in the literature as effective for the preparation of Guerbet Alcohols. These catalysts, hereafter referred to as Guerbet catalysts, include, nickel, lead salts (U.S. Pat. No. 3,119,880), oxides of copper, lead, zinc, chromium, molybdenum, tungsten, and manganese (U.S. Pat. No. 3,558,716), palladium compounds and silver compounds, and many others U.S. Pat. No. 3,979,466 and U.S. Pat. No. 3,864,407), and mixtures thereof. All patents are incorporate herein by reference.
As can be seen by the above reaction the molecules have substitution on the second carbon from the hydroxyl group. This branching has been found to be critical to the preparation of a product having the desired lubrication and oxidative stability properties. If the branching were on the same carbon as the hydroxyl group, the hydroxyl group would be a secondary one and would be very hindered and has low reactivity. As one moves the branch position away from the beta carbon, the liquidity, lubricity and metal substantivity decreases. If the branch is lower alkyl like methyl in some oxo alcohols, there is little increase in the liquidity, lubricity and metal substantivity over normal alcohols having the same number of carbons. Additionally, the oxo process gives only some beta branching (between 1 and 28%) the Guerbet process gives essentially 100% product.
As should be apparent from the above reaction, the Guerbet reaction takes two moles of a primary alcohol and condenses them to make a regiospecific beta branched primary alcohol of twice the molecular weight. The present invention surprisingly makes use of this reaction sequence, but on a diol, in which the reaction occurs on both sides of the molecule. This results in a polymerization reaction increasing molecular weight, introducing beta branching and doubling the molecular weight. The reaction proceeds with the diol until the mono substituted alcohol reacts and caps the sequence. By modification of the ratio of capper to diol the molecular weight is controlled. As the concentration of capper increases the molecular weight decreases.
Guerbet alcohols have unusual properties. These unique properties are partly attributed to their high molecular weight and high level of saturation (A. J. O'Lenick Jr. and R. E. Bilbo, Soap/Cosmetics/Chemical Specialties, April 1987, page 52). Unusual properties are attributed to the so called “beta branch point”. Some of the properties attributed to Guerbet alcohols are low irritation, liquidity to extremely low temperatures, low volatility, relatively reactive and easy to derivitize, useful superfatting agents to re-oil the skin and hair, highly lipophilic, good oxidation stability, and excellent color stability.
U.S. Pat. No. 4,425,458 issued in 1984 to Lindner et al teaches that certain Guerbet alcohol diesters are useful as plastic lubricants.
U.S. Pat. No. 4,731,190 issued in 1988 and U.S. Pat. No. 4,830,769 both issued to O'Lenick et al, and incorporated herein by reference, teaches that certain Guerbet alcohol alkoxylates are useful as metal working lubricants.
U.S. Pat. No. 4,868,236 issued in 1989 to O'Lenick teaches that certain Guerbet alcohol citrate esters are useful as plastic lubricants.
U.S. Pat. No. 4,800,077 issued in 1989 to O'Lenick et al, which is incorporated herein by reference, teaches that certain Guerbet alcohol based quaternary compounds are useful liquid cosmetic and personal care compounds.
U.S. Pat. No. 5,488,121 to O'Lenick, incorporated herein by reference, discloses di-guerbet esters based upon the reaction product of both a Guerbet acid and a Guerbet alcohol.
U.S. Pat. No. 5,786,389 issued in 1998 to O'Lenick et al, incorporated herein by reference, teaches that certain castor esters made by the reaction of a Guerbet alcohol and castor oil provide gloss to the skin.
Despite the considerable patenting of products based upon Guerbet alcohol technology, it was not until the present invention that the Guerbet reaction sequence has been utilized to produce polymeric materials by the reaction of a diol, which functions as a chain extender, and a fatty alcohol that functions as a chain terminator. The reaction provides highly branched, oxidatively stable, oil phases with many hydroxyl groups.
The compounds of the present invention are outstanding lubricating oils, and also find application in the cosmetic arts as superfatting materials. They replenish oils into the skin when applied topically. Another key use for the compounds of the present invention is as raw materials for preparation of esters.